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<div class="section" id="pair">
<h1><a class="toc-backref" href="./data-types-miscellaneous.html#id1583">pair</a></h1>
<div class="section" id="id1271">
<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
<pre class="literal-block">
template&lt;
      typename T1
    , typename T2
    &gt;
struct <a href="./pair.html" class="identifier">pair</a>
{
    typedef <a href="./pair.html" class="identifier">pair</a> type;
    typedef T1 first;
    typedef T2 second;
};
</pre>
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<div class="section" id="id1272">
<h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
<p>A transparent holder for two arbitrary types.</p>
</div>
<div class="section" id="id1273">
<h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
<pre class="literal-block">
#include &lt;<a href="../../../../boost/mpl/pair.hpp" class="header">boost/mpl/pair.hpp</a>&gt;
</pre>
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<div class="section" id="id1274">
<h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
<p>Count a number of elements in the sequence together with a number of negative
elements among these.</p>
<pre class="literal-block">
typedef <a href="./fold.html" class="identifier">fold</a>&lt;
      <a href="./vector-c.html" class="identifier">vector_c</a>&lt;int,-1,0,5,-7,-2,4,5,7&gt;
    , <a href="./pair.html" class="identifier">pair</a>&lt; <a href="./int.html" class="identifier">int_</a>&lt;0&gt;, <a href="./int.html" class="identifier">int_</a>&lt;0&gt; &gt;
    , <a href="./pair.html" class="identifier">pair</a>&lt;
          <a href="./next.html" class="identifier">next</a>&lt; first&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt; &gt;
        , <a href="./if.html" class="identifier">if_</a>&lt;
              <a href="./less.html" class="identifier">less</a>&lt; <a href="./placeholders.html" class="identifier">_2</a>, <a href="./int.html" class="identifier">int_</a>&lt;0&gt; &gt;
            , <a href="./next.html" class="identifier">next</a>&lt; second&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt; &gt;
            , second&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt;
            &gt;
        &gt;
    &gt;::type p;

<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( p::first::value, ==, 8 );
<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( p::second::value, ==, 3 );
</pre>
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<div class="section" id="id1275">
<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
<p><a class="reference internal" href="./data-types.html">Data Types</a>, <a class="reference internal" href="./sequences.html">Sequences</a>, <a class="reference internal" href="./trivial-metafunctions-summary.html#first">first</a>, <a class="reference internal" href="./trivial-metafunctions-summary.html#second">second</a></p>
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